Protein expression levels of membrane proteins in brain capillaries isolated from C57BL/6 WT and hMDR1 mice.

<p>Brain capillary was isolated from the pooled frozen brains of 10 mice by means of nylon mesh method. Brain capillary passing through an 85 μm nylon mesh and retained on a 20 μm nylon mesh was collected, and digested with lysyl endopeptidase and trypsin. The digest was subjected to LC-MS/MS analysis with internal standard peptides. The each target peptide was monitored with four different SRM/MRM transitions. The preparation of pooled brain capillary from 10 mice was conducted only one time. For the pooled brain capillary, the digestion followed by LC-MS/MS analysis was repeated three times. The protein expression level of target molecule was determined as an average and variability (mean ± S.E.M.) of the quantitative values obtained from different SRM/MRM transitions in three analyses. Therefore, the S.E.M. represents the variability of protein expression level determined in different MS/MS transitions in three analyses, but does not represent the inter-individual variability.</p><p>U.L.Q., under the limit of quantification.</p><p>*<i>p</i> < 0.01, significantly different from the C57BL/6 WT mice.</p><p>^a measured by using a peptide probe set specific for human MDR1.</p><p>^b measured by using a peptide probe set specific for mouse mdr1a.</p><p>^c measured by using a peptide probe set common for human MDR1 and mouse mdr1a.</p><p>Protein expression levels of membrane proteins in brain capillaries isolated from C57BL/6 WT and hMDR1 mice.